This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The main objective of this trial is to use MRI measurements of tumor response to uniquely identify two groups of participants who have statistically different three-year disease-free survival out of a group of participants with Stage III breast cancer who demonstrate a partial or minimal clinical response (as identified by physical examination) to neoadjuvant chemotherapy. The objective of the ACRIN 6657 protocol extension is to investigate the usefulness of total choline concentration [tCho] measured by 1H MRS early in the course of treatment, for predicting pathologic response. Following completion of accrual to the original 6657 protocol, an additional group of patients meeting the same eligibility criteria as in the original protocol are being enrolled to the protocol extension. Three changes to the imaging protocol have been made: 1) addition of a single voxel 1H MRS acquisition and optional diffusion-weighted MRI acquisition to the MRI exam, 2) reduction of the number of (6657 study-related) imaging exams from 4 to 3 during the course of treatment, and 3) change of the timing of the post 1st cycle MRI/MRS exam.